The problem of debris collecting within gutters is well documented. Many different forms of gutter debris preclusion systems, often referred to as “gutter guards,” have been developed to discourage debris from collecting within the gutter. Some such gutter guards are of a type which provide merely a rigid barrier with holes therein so that water can pass through but debris cannot. Such simple systems suffer from the serious drawback that the holes must be large enough that water will pass through rather than adhering due to surface tension and adhesion forces to edges of the holes. On the other hand, the holes must be small enough to prevent debris from passing therethrough. Experience has shown that the compromises required with such simple gutter guard systems lead to serious deficiencies in the performance of such gutter guard systems, either not effectively allowing water to pass therethrough or too often allowing debris to pass therethrough.
Other gutter guard systems utilize solid rigid layers of material with a sharp curve in the surface which water can adhere to, but which debris will not adhere to. Water adheres to the sharply curving metal portion and is routed in a curving path into the gutter, while debris falls off of such a gutter guard. Such gutter guards have advantages and disadvantages which are well documented in the prior art.
A third form of gutter guard known in the prior art utilizes a fine mesh filter element which has sufficiently small holes therein that debris cannot pass therethrough and this fine mesh filter element, which is formed as a thin flexible screen material, is supported upon a rigid underlying support structure that holds the filter element in place, with the underlying support structure having holes therein to route water passing through the filter element down through the support structure and into the gutter. Such two part filter and support structure gutter guards beneficially allow substantially all debris to be precluded from the gutter while allowing high volumes of water to be routed into the gutter. Examples of such gutter guards include those described in U.S. Pat. No. 7,310,912, incorporated herein by reference in its entirety.
One problem experienced by all different types of gutter guard systems in certain environments is that when freezing temperatures are encountered, water on and adjacent the gutter guard will freeze, and preclude water from passing into the gutter. When such gutter guard performance is inhibited, freeze and thaw cycles can result in dangerously large icicles forming off of edges of the gutters or other portions of the roof. Furthermore, the weight of the snow and ice on the gutter guard can potentially damage the gutter or gutter guard, or at least require that it be designed to withstand high loads, increasing the complexity, and cost of the gutter guards.
Another problem with non-de-icing gutter guards is “ice dams” can form. When the heat of the interior of the home is on to warm the house so people feel comfortable, the heat radiates to the roof and begins melting the snow. The melted snow run-off goes down the roof and when it passes the imaginary line of the building wall, the melted snow then encounters the freezing roof again and begins to freeze, building up a wall of frozen water. Then the water begins to pool above the ice dam and then the melted snow has nowhere else to go but to find it's way through the roof and into the home, causing damage.
One solution for de-icing gutters and gutter guards is to utilize wire which transmits heat to adjacent structures when electric power is routed therethrough. In at least one case, a gutter guard of the curving metal cover type has had such a resistive heating wire integrated into the gutter guard so that the surface of the gutter guard could conduct heat from the resistance heating wire to melt frozen water off of the gutter. Such a system is described in U.S. Pat. No. 7,448,167, incorporated by reference herein in its entirety.
Because such curving metal style gutter guards have a single layer of metal forming the entire gutter guard, the wires can simply heat surfaces which come in contact with the frozen water. However, such a solution is not applicable to multi-part gutter guard systems, such as those described below which include a filter element and an underlying support structure. In particular, filter elements are beneficially formed from materials which resist corrosion. Such materials are also generally low in thermal conductance. For instance, of all metals, stainless steel is known for its low corrosion characteristics, but is also known for being very low in thermal conductance, especially for a steel alloy. Such low thermal conductance of screen materials can require either excessive electric power to be routed to the gutter guard system to cause ice thereon to be melted, or suffers from lack of sufficient heat transfer, so that only limited melting of frozen water occurs. Accordingly, a need exists for a gutter debris preclusion system which has the benefit of a filter and underlying support structure style of gutter guard, and which also can effectively be de-iced so that the system can perform when frozen water is experienced, and ameliorate the problem of ice dam formation.